Pharmaceutical dosage forms comprising descarboethoxyloratadine

ABSTRACT

Methods utilizing descarboethoxyloratadine (“DCL”) for the treatment of allergic disorders, while avoiding the concomitant liability of adverse side-effects associated with other non-sedating antihistamines. Also included are methods for the treatment of allergic asthma using DCL and either a decongestant or a leukotriene inhibitor, while avoiding the concomitant liability of adverse side-effects associated with other non-sedating antihistamines. The invention also encompasses the administration of DCL in a nasal or oral spray.

1. FIELD OF THE INVENTION

[0001] The present invention relates to methods of treatment involvingthe administration of a therapeutically effective amount of a metabolicderivative of loratadine known as descarboethoxyloratadine.

2. DESCRIPTION OF THE RELATED ART

[0002] Loratadine is an antagonist of the H-1 histamine receptorprotein. The histamine receptors H-1 and H-2 are two well-identifiedforms. The H-1 receptors are those that mediate the response antagonizedby conventional antihistamines. H-1 receptors are present, for example,in the ileum, the skin, and the bronchial smooth muscle of man and othermammals.

[0003] Loratadine binds preferentially to peripheral rather than tocentral H-1 receptors. Quercia et al., Hosp. Formul. 28: 137-53 (1993).Loratadine has been shown to be a more potent inhibitor ofserotonin-induced bronchospasm in guinea pigs than terfenadine. Id. at137-38. Its anti-allergenic activity in animal models was shown to becomparable to that of terfenadine and astemizole. Id. at 138. However,using standard animal model testing, on a milligram by milligram basis,loratadine was shown to be four times more potent than terfenadine inthe inhibition of allergic bronchospasm. Id. Moreover, loratadine'santihistaminic activity was demonstrated in humans by evaluation of thedrug's ability to suppress wheal formation. Id. Clinical trials ofefficacy indicated that loratadine is an effective H-1 antagonist. SeeClissold et al., Drugs 37: 42-57 (1989).

[0004] Through H-2 receptor-mediated responses, histamine stimulatesgastric acid secretion in mammals and the chronotropic effect inisolated mammalian atria. Loratadine has no effect on histamine-inducedgastric acid secretion, nor does it alter the chronotropic effect ofhistamine on atria. Thus. loratadine has no apparent effect on the H-2histamine receptor.

[0005] Loratadine is well absorbed but is extensively metabolized.Hilbert, et al., J. Clin. Pharmacol. 27: 694-98 (1987). The mainmetabolite, DCL, which has been identified, is reported to bepharmacologically active. Clissold, Drugs 37: 42-57 (1989). It is alsoreported as having antihistaminic activity in U.S. Pat. No. 4,659,716.This patent recommends an oral dosage range of 5 to 100 mg/day andpreferably 10 to 20 mg/day.

[0006] Loratadine's efficacy in treating seasonal allergic rhinitis iscomparable to that of terfenadine. Quercia et al., Hosp. Formul. 28:137, 141 (1993). Loratadine also has a more rapid onset of action thanastemizole. Id.

[0007] Clissold et al., Drugs 37: 42, 50-54 (1989) describes studiesshowing loratadine as effective for use in seasonal and perennialrhinitis, colds (with pseudoephedrine), and chronic urticaria. It hasalso been suggested that loratadine would be useful for the treatment ofallergic asthma. Temple et al. Prostaglandins 35: 549-554 (1988).

[0008] Loratadine may also be useful for the treatment of motionsickness and vertigo. Some antihistamines have been found to beeffective for the prophylaxis and treatment of motion sickness. SeeWood, Drugs, 17: 471-79 (1979). Some antihistamines have also provenuseful for treating vestibular disturbances, such as Meniere's disease,and in other types of vertigo. See Cohen et al., Archives of Neurology,27: 129-35 (1972).

[0009] In addition, loratadine may be useful in the treatment ofdiabetic retinopathy and other small vessel disorders associated withdiabetes mellitus. In tests on rats with streptozocin-induced diabetes,treatment by antihistamines prevented the activation of retinalhistamine receptors which have been implicated in the development ofdiabetic retinopathy. The use of antihistamines to treat retinopathy andsmall vessel disorders associated with diabetes mellitus is disclosed inU.S. Pat. No. 5,019,591.

[0010] It has also been suggested that loratadine, in combination withnon-steroidal antiinflammatory agents or other non-narcotic analgesics,would be useful for the treatment of cough, cold, cold-like and/or flusymptoms and the discomfort, pain, headache, fever, and general malaiseassociated therewith.

[0011] Many antihistamines cause adverse side-effects. These adverseside-effects include, but are not limited to, sedation, gastrointestinaldistress, dry mouth, constipation or diarrhea. Loratadine has been foundto cause relatively less sedation as compared with other,antihistamines. Moreover, the incidence of fatigue, headache, and nauseawas is similar to those observed for terfenadine. See Quercia et al.,Hosp. Formul. 28: 137,142 (1993).

[0012] Furthermore, compounds within the class of non-sedatingantihistamines, including loratadine, astemizole, and terfenadine, havebeen known to cause other severe adverse electrophysiologicside-effects. These adverse side-effects are associated with a prolongedQT interval and include but are not limited to ventricular fibrillationand cardiac arrhythmias, such as ventricular tachyarrhythmias ortorsades de pointes. Knowles, Canadian Journal Hosp. Pharm., 45: 33,37(1992); Craft, British Medical Journal, 292: 660 (1986); Simons et al.,Lancet, 2: 624 (1988); and Unknown, Side Effects of Drugs Annual, 12:142 and 14: 135.

[0013] Quercia et al., Hosp. Formul. 28: 137, 142 (1993) noted thatserious cardiovascular adverse side-effects, including torsades depointes and other ventricular arrhythmias, were reported in “healthy”patients who received terfenadine concurrently with either ketoconazoleor erythromycin. Quercia et al., also states that arrhythmias have alsobeen reported with the concomitant administration of astemizole anderythromycin or erythromycin plus ketoconazole. Thus, he cautionsagainst using loratadine concurrently with ketoconazole, itraconazole,and macrolides, such as erythromycin.

[0014] Additionally, it is also known that ketoconazole and/orerythromycin interfere with cytochrome P450, and thereby inhibit themetabolism of non-sedative antihistamines such as terfenadine andastemizole. Because of the interference with the metabolism ofloratadine, there exists a greater potential for adverse interactionbetween loratadine or other non-sedating antihistamines and drugs knownto inhibit cytochrome P450, such as but not limited to ketoconazole,itraconazole, and erythromycin.

[0015] In Brandes et al., Cancer Res. (52) 3796-3800 (1992), Brandesshowed that the propensity of drugs to promote tumor growth in vivocorrelated with potency to inhibit concanavalin A stimulation oflymphocyte mitogenesis. In Brandes et al., J. Nat'l Cancer Inst.,86(10): 771-775 (1994), Brandes assessed loratadine in an in vitro assayto predict enhancement of in vivo tumor growth. He found that loratadineand astemizole were associated with growth of both melanoma andfibrosarcoma tumors. The dose for loratadine in this study was 10mg/day.

[0016] Thus, it would be particularly desirable to find methods oftreatment with the advantages of known non-sedating antihistamines whichwould not have the aforementioned disadvantages.

3. SUMMARY OF THE INVENTION

[0017] The present invention provides methods and compositions involvingdescarboethoxyloratadine, i.e.,8-chloro-6,11-dihydro-11-(4-piperidylidene)-5H-benzo[5,6]cyclohepta[1,2-b]pyridine(“DCL”). This compound is specifically described in Quercia, et al.Hosp. Formul., 28: 137-53 (1993) and U.S. Pat. No. 4,659,716.

[0018] In one aspect, this invention provides, a method of treatingallergic asthma in a human while avoiding the concomitant liability ofadverse side-effects associated with the administration of non-sedatingantihistamines, comprising administering to a human a composition, saidcomposition comprising (i) a therapeutically effective amount of DCL ora pharmaceutically acceptable salt thereof; (ii) a therapeuticallyeffective amount of a decongestant; and a pharmaceutically acceptablecarrier.

[0019] The invention also provides a method of treating allergic asthmain a human while avoiding the concomitant liability of adverseside-effects associated with the administration of non-sedatingantihistamines, comprising administering to a human a composition, saidcomposition comprising (i) a therapeutically effective amount of DCL ora pharmaceutically acceptable salt thereof; (ii) a leukotriene inhibitorselected from the group consisting of 5-lipoxygenase inhibitors,5-lipoxygenase activating protein antagonists, and leukotriene D₄antagonists; and a pharmaceutically acceptable carrier.

[0020] This invention is also directed to a method of treating allergicasthma in a human while avoiding the concomitant liability of adverseside-effects associated with the administration of non-sedatingantihistamines, comprising administering to a human a therapeuticallyeffective amount of DCL and a therapeutically effective amount of adecongestant.

[0021] Additionally, this invention provides for a method of treatingallergic asthma in a human while avoiding the concomitant liability ofadverse side-effects associated with the administration of non-sedatingantihistamines, comprising administering to a human a therapeuticallyeffective amount of DCL and a therapeutically effective amount of aleukotriene inhibitor.

[0022] This invention also provides for a method of treating dermatitisin a human while avoiding the concomitant liability of adverseside-effects associated with the administration of non-sedatingantihistamines, comprising administering to a human a therapeuticallyeffective amount of DCL or a pharmaceutically acceptable salt thereof.

4. DETAILED DESCRIPTION OF THE INVENTION

[0023] The present invention encompasses a method of treating allergicasthma in a human while avoiding the concomitant liability of adverseside-effects associated with the administration of non-sedatingantihistamines, comprising administering to a human a composition, saidcomposition comprising (i) a therapeutically effective amount of DCL ora pharmaceutically acceptable salt thereof; (ii) a therapeuticallyeffective amount of a decongestant; and a pharmaceutically acceptablecarrier. DCL and a decongestant may also be administered separately inthe method of treating allergic asthma. For example, DCL and adecongestant may be administered concurrently or sequentially, i.e., DCLand a decongestant may be administered in combination eitherconcurrently or by the sequential administration of DCL and decongestantor the sequential administration of a decongestant and DCL.

[0024] Thus, the present invention also encompasses a method of treatingallergic asthma in a human while avoiding the concomitant liability ofadverse side-effects associated with the administration of non-sedatingantihistamines, comprising administering to a human a therapeuticallyeffective amount of DCL and a therapeutically effective amount of adecongestant.

[0025] The present invention also relates to a method of treatingallergic asthma in a human while avoiding the concomitant liability ofadverse side-effects associated with the administration of non-sedatingantihistamines, comprising administering to a human a composition, saidcomposition comprising (i) a therapeutically effective amount of DCL ora pharmaceutically acceptable salt thereof; (ii) a therapeuticallyeffective amount of a leukotriene inhibitor selected from the groupconsisting of 5-lipoxygenase (“5-LO”) inhibitors, 5-lipoxygenaseactivating protein (“FLAP”) antagonists, and leukotriene D₄ (“LTD₄”)antagonists; and a pharmaceutically acceptable carrier. Theadministration of DCL and a leukotriene inhibitor in the methods of thepresent invention for treating allergic asthma may be eitherconcurrently or sequentially, i.e., DCL and a leukotriene inhibitor maybe administered as a combination, concurrently but separately, or by thesequential administration of DCL and leukotriene inhibitor or thesequential administration of a leukotriene inhibitor and DCL.

[0026] Thus, the present invention encompasses a method of treatingallergic asthma in a human while avoiding the concomitant liability ofadverse side-effects associated with the administration of non-sedatingantihistamines, comprising administering to a human a therapeuticallyeffective amount of DCL and a therapeutically effective amount of aleukotriene inhibitor.

[0027] A further aspect of the present invention includes a method oftreating dermatitis in a human while avoiding the concomitant liabilityof adverse side-effects associated with the administration ofnon-sedating antihistamines, comprising administering to a human atherapeutically effective amount of DCL or a pharmaceutically acceptablesalt thereof.

[0028] The side-effects to be avoided by the methods of the presentinvention include but are not limited to, cardiac arrythmia and tumorpromotion. It has been found that when DCL is concurrently administeredwith a drug that inhibits cytochrome P450 including but not limited toketoconazole, itraconazole, erythromycin and others known by thoseskilled in the art, the drug-drug interactions are decreased incomparison to the concurrent administration of loratadine or othernon-sedating antihistamines with said drug. Thus, the methods of thepresent invention as described above are particularly useful in thetreatment of allergic disorders such as dermatitis and asthma in a humanhaving a higher than normal propensity for or incidence of cancer and/orwhile avoiding interaction with a drug that inhibits cytochrome P450.

[0029] The present invention also includes novel compositions for use inthe methods described above.

[0030] It has been found that DCL is at least about twenty times morepotent at the histamine receptor when compared to loratadine. Thus, thedosage range by the modes of administration described herein and for usein the methods of the present invention, are about 0.1 to less thanabout 10 mg per day. This dosage range is significantly lower than whatas been recommended for other non-sedating antihistamines, includingloratadine which has a recommended oral dose of 5 to 100 mg per day.However, due to the significantly less side-effects, DCL can be given indoses higher than those suggested for loratadine thereby offering animproved therapeutic range than loratadine.

[0031] Loratadine and other non-sedating antihistamines haveantihistaminic activity and provide therapy and a reduction of symptomsfor a variety of conditions and disorders related to allergic rhinitisand other allergic disorders, diabetes mellitus and other conditions;however, such drugs, while offering the expectation of efficacy, causeadverse side-effects. Utilizing DCL results in clearer dose-relateddefinitions of efficacy, diminished adverse side-effects, andaccordingly, an improved therapeutic index. It is, therefore, moredesirable to use DCL than to use loratadine itself or other non-sedatingantihistamines.

[0032] The term “adverse effects” includes, but is not limited to tumorpromotion, cardiac arrhythmias, cardiac conduction disturbances,appetite stimulation, weight gain, sedation, gastrointestinal distress,headache, dry mouth, constipation, and diarrhea. The term “cardiacarrhythmias” includes, but is not limited to ventriculartachyarrhythmias, torsades de pointes, and ventricular fibrillation.

[0033] The phrase “therapeutically effective amount” means that amountof DCL which provides a therapeutic benefit in the treatment ormanagement of allergic disorders such as urticaria, allergic rhinitis,symptomatic dermographism, dermatitis, allergic asthma, retinopathy orother small vessel disorders associated with diabetes mellitus, and thesymptoms associated with allergic rhinitis such as cough, cold,cold-like, and/or flu symptoms including, but not limited to, sneezing,rhinorrhea, lacrimation, and dermal irritation.

[0034] The term “allergic asthma” is defined as a disorder characterizedby increased responsiveness of the trachea and bronchi to variousstimuli which results in symptoms which include wheezing, cough, anddyspnea.

[0035] The term “dermatitis” is that disorder caused by inflammation tothe skin including endogenous and contact dermatitis such as, but notlimited to: actinic dermatitis (or photodermatitis), atopic dermatitis,chemical dermatitis, cosmetic dermatitis, dermatitis aestivalis, andseborrheic dermatitis.

[0036] The term “leukotriene inhibitor” includes any agent or compoundthat inhibits, restrains, retards or otherwise interacts with the actionor activity of leukotrienes, such as, but not limited to, 5-lipoxygenase(“5-LO”) inhibitors, 5-lipoxygenase activating protein (“FLAP”)antagonists, and leukotriene D₄ (“LTD₄”) antagonists.

[0037] The term “5-lipoxygenase inhibitor” or “5-LO inhibitor” includesany agent or compound that inhibits, restrains, retards or otherwiseinteracts with the enzymatic action of 5-lipoxygenase, such as, but notlimited to, zileuton, docebenone, piripost, and ICI-D2318.

[0038] The term “5-lipoxygenase activating protein antagonist” or “FLAPantagonist” includes any agent or compound that inhibits, restrains,retards or otherwise interacts with the action or activity of5-lipoxygenase activating protein, such as, but not limited to MK-591and MK-886.

[0039] The term “leukotriene D₄ antagonist” or “LTD₄ antagonist”includes any agent or compound that inhibits, restrains, retards orotherwise interacts with the action or activity of leukotriene D₄ , suchas but not limited to zarfirlukast (ICI-204219).

[0040] The magnitude of a prophylactic or therapeutic dose of DCL in theacute or chronic management of an allergic disorder or condition willvary with the severity of the condition to be treated and the route ofadministration. The dose, and perhaps the dose frequency, will also varyaccording to the age, body weight, and response of the individualpatient. Suitable total daily dose ranges can be readily determined bythose skilled in the art. In general, the total daily dose range forDCL, for the conditions described herein, is from about 0.1 mg to lessthan about 10 mg administered in single or divided doses orally,topically, transdermally, or locally by inhalation. For example, apreferred oral daily dose range should be from about 0.1 mg to about 5mg. A more preferred oral dose is about 0.2 mg to about 1 mg. Apreferred oral daily dose range of decongestant, such aspseudoephedrine, should be from about 50 mg to about 300 mg, morepreferably, about 150 mg to about 250 mg. In addition, suitable oraldaily dosage ranges of leukotriene inhibitor can be readily determinedby those skilled in the art.

[0041] It is further recommended that children, patients aged over 65years, and those with impaired renal or hepatic function initiallyreceive low doses, and that they then be titrated based on individualresponse(s) or blood level(s). It may be necessary to use dosagesoutside these ranges in some cases as will be apparent to those skilledin the art. Further, it is noted that the clinician or treatingphysician will know how and when to adjust, interrupt, or terminatetherapy in conjunction with individual patient response.

[0042] The term “therapeutically effective amount of DCL or apharmaceutically acceptable salt thereof” is encompassed by theabove-described dosage amounts. In addition, the terms “said compositioncomprising (i) a therapeutically effective amount of DCL or apharmaceutically acceptable salt thereof; and (ii) a therapeuticallyeffective amount of a decongestant”; and “said composition comprising(i) a therapeutically effective amount of DCL or a pharmaceuticallyacceptable salt thereof; and (ii) a therapeutically effective amount ofa leukotriene inhibitor” are also encompassed by the above-describeddosage amounts and dose frequency schedule.

[0043] Any suitable route of administration may be employed forproviding the patient with an effective dosage of DCL according to themethods of the present invention. For example, oral, intraoral, rectal,parenteral, epicutaneous, transdermal, subcutaneous, intramuscular,intranasal, sublingual, intradural, intraocular, intrarespiratory, oralor nasal inhalation and like forms of administration may be employed.For the methods to treat dermatitis topical administration is preferred.

[0044] The pharmaceutical compositions used in the methods of thepresent invention comprise DCL, the metabolic derivative of loratadine,as active ingredient, or a pharmaceutically acceptable salt thereof, andmay also contain a pharmaceutically acceptable carrier, and optionally,other therapeutic ingredients

[0045] The term “pharmaceutically acceptable salt” refers to a saltprepared from pharmaceutically acceptable non-toxic acids or basesincluding inorganic acids or bases or organic acids or bases. Examplesof such inorganic acids are hydrochloric, hydrobromic, hydroiodic,sulfuric, and phosphoric. Appropriate organic acids may be selected, forexample, from aliphatic, aromatic, carboxylic and sulfonic classes oforganic acids, examples of which are formic, acetic, propionic,succinic, glycolic, glucuronic, maleic, furoic, glutamic, benzoic,anthranilic, salicylic, phenylacetic, mandelic, embonic (pamoic),methanesulfonic, ethanesulfonic, pantothenic, benzenesulfonic, stearic,sulfanilic, algenic, and galacturonic. Examples of such inorganic basesinclude metallic salts made from aluminum, calcium, lithium, magnesium,potassium, sodium, and zinc. Appropriate organic bases may be selected,for example, from N,N-dibenzylethylenediamine, chloroprocaine, choline,diethanolamine, ethylenediamine, meglumaine (N-methylglucamine), lysineand procaine.

[0046] The compositions for use in the methods of the present inventioncan include suitable excipients or carriers such as starches, sugars,microcrystalline cellulose, diluents, granulating agents, lubricants,binders, disintegrating agents, and the like.

[0047] Dosage forms include tablets, troches, dispersions, suspensions,solutions, capsules, patches, syrups, elixirs, gels, powders, magmas,lozenges, ointments, creams, pastes, plasters, lotions, discs,suppositories, nasal or oral sprays, aerosols and the like.

[0048] Because of their ease of administration, tablets and capsulesrepresent the most advantageous oral dosage unit form, in which casesolid pharmaceutical carriers are employed. If desired, tablets may becoated by standard aqueous or nonaqueous techniques.

[0049] In addition to the common dosage forms set out above, thecompound for use in the methods of the present invention may also beadministered by controlled release means and/or delivery devices such asthose described in U.S. Pat. Nos. 3,845,770; 3,916,899; 3,536,809;3,598,123; and 4,008,719, the disclosures of which are herebyincorporated by reference.

[0050] Pharmaceutical compositions for use in the methods of the presentinvention may be prepared by any of the methods of pharmacy, but allmethods include the step of bringing into association the activeingredient with the carrier which constitutes one or more necessaryingredients. In general, the compositions are prepared by uniformly andintimately admixing the active ingredient with liquid carriers or finelydivided solid carriers or both, and then, if necessary, shaping theproduct into the desired presentation.

[0051] For example, a tablet may be prepared by compression or molding,optionally, with one or more accessory ingredients. Compressed tabletsmay be prepared by compressing in a suitable machine the activeingredient in a free-flowing form such as powder or granules, optionallymixed with a binder, lubricant, inert diluent, surface active ordispersing agent. Molded tablets may be made by molding, in a suitablemachine, a mixture of the powdered compound moistened with an inertliquid diluent. Desirably, each tablet contains from about 0.1 mg toless than about 10 mg of the active ingredient, and each cachet orcapsule contains from about 0.1 mg to about less than 10 mg of the DCL.

[0052] The invention is further defined by reference to the followingexamples describing in detail the preparation of the compound and thecompositions used in the methods of the present invention, as well astheir utility. It will be apparent to those skilled in the art that manymodifications, both to materials and methods, may be practiced which arewithin the scope of this invention.

5. EXAMPLES 5.1 Example 1 Preparation of Loratadine and its Metabolites

[0053] Loratadine can be synthesized by methods disclosed in U.S. Pat.No. 4,282,233. The metabolites are prepared similarly, by reaction stepsconventional in the art, as described in U.S. Pat. No. 4,659,716 whichis incorporated here by reference in its entirety. One common method ofpreparing DCL is to reflux loratadine in the presence of sodiumhydroxide and ethanol as depicted below.

Extraction of Commercially Available Claritin Tablets (600×10 mg)

[0054] Tablets of loratadine, were diluted with water and chloroform.The mixture was stirred, then filtered through celite, rinsed withchloroform until the filtrate contained no loratadine. The separatedaqueous layer was extracted with chloroform twice. The combined organiclayer was washed with water, brine and dried over sodium sulfate. Thesolvent was evaporated to give pure loratadine as a white solid.

Saponification of Loratadine

[0055] Loratadine (4.0 g) was added to a solution of sodium hydroxide(5.9 g) in 280 mL of absolute ethanol and the mixture was stirred atreflux for four days. The mixture was cooled and concentrated to removeethanol. The residue was diluted with water and aqueous layer wasextracted with methylene chloride five times. The combined organic layerwas washed with water, brine and dried over sodium sulfate. The solventwas evaporated to give 2.82 g (87%) of pure loratadine derivative (ormetabolite) as a pale-tan solid.

5.2 Example 2 Antihistaminic Activity

[0056] The antihistaminic activity of loratadine and DCL were comparedin isolated strips of guinea pig ileum contracted with histamine. Thispreparation is generally accepted by those skilled in the art aspredicative of its efficacy as a peripheral histamine H-1 receptor.

Methods

[0057] Experiments were performed on pieces of ileum taken from maleguinea pigs (Hartley strain, 419-560 grams; Elm Hill BreedingLaboratories, Chelmsford, Mass.). The tissues were suspended in tissuechambers containing 40 ml of Tyrode's solution aerated with 95% oxygenand 5% carbon dioxide at 35° C. The Tyrode's solution contained (in mM)137 NaCl, 2.7 KCl, 2.2 CaCl₂, 0.025 MgCl₂, 0.4 NaHPO₄, 11.9 NaHCO₃ and5.5 glucose. Contractions in response to histamine were recorded withisotonic transducers (Model 357, Harvard Apparatus Company, SouthNatick, Mass.) using an ink-writing polygraph (Model 7, Grass InstrumentCompany, Quincy, Mass.). A tension of one gram was maintained on alltissues at all times.

[0058] In each experiment three or four pieces of ileum were removedfrom a single animal, suspended in individual tissue chambers andallowed to equilibrate with the bathing solution for one hour before theadministration of any drugs. In four initial experiments in whichtissues were exposed to histamine at concentrations of 1×10⁻⁷, 1×10⁻⁶,and 1×10⁻⁵ mol/l, histamine at 1×10⁻⁶ mol/l produced strong contractionson the linear portion of the log-concentration-effect curve and thisconcentration of histamine was chosen for use in all furtherexperiments.

[0059] For determining the antihistaminic effects of loratadine and DCL,tissues were exposed briefly (about 15 seconds) to 1×10⁻⁶ mol/l ofhistamine at intervals of 15 minutes. After two successive exposures tohistamine produced contractions of approximately the same magnitude,loratadine or DCL, at final concentrations that varied three- orten-fold, was added to all but one of the tissue chambers, the untreatedtissue serving as a control for the treated tissues. After each exposureof drug-treated tissues to histamine, the fluid in the tissue chamberwas replaced with fluid free of histamine but containing the same drugat the same concentration. The histamine challenges were made at 5, 20,35, 50, 65, 80, 95, 110 and 125 minutes of exposure to the drug or atcomparable times in the control tissues.

[0060] Subsequent analyses of the results from each experiment involved(i) normalization of the data from each tissue for differences ininherent contractility by expressing all contractions as a percent ofthe last predug contraction, (ii) normalization of the data for possibletime-related changes in contractility by expressing the contractionsrecorded during drug-exposure as a percent of the corresponding valuefor the untreated tissue, and finally (iii) calculation of thedrug-related percent reduction of each contraction.

[0061] The resultant sets of data for drug concentration andcorresponding percent reduction in histamine-response were then used toestimate for each experiment the concentration of drug that would haveproduced a 50 percent reduction in the histamine response, the IC₅₀.This was done by fitting straight lines to the data using the method ofleast squares and calculating the IC₅₀ from the equation of the line.The mean+/−standard error of the values for the experiments on each drugwere calculated, and differences between the drugs was examined usingthe Kruskal Wallis 1-way analysis of variance by ranks.

[0062] A summary of the results are shown in the following two tables.The percentages of reduction of histamine-induced contractions of theisolated guinea pig ileum produced by exposure for 125 minutes tovarious concentrations of each drug are set forth below: TABLE 1Reduction of Histamine-induced Guinea pig Ileum Contractions (Percent)Expt Concentration of drug (mol/1) Drug No. 3 × 10⁻¹⁰ 1 × 10⁻⁹ 3 × 10⁻⁹1 × 10⁻⁸ 3 × 10⁻⁸ 1 × 10⁻⁷ Loratadine 1 — 19.05 — 13.33 — 88.57 2 — — —28.32 54.42 98.66 3 — — — 39.64 44.68 93.38 4 — — — 55.86 45.83 86.46DCL 1 11.93 73.12 2 38.91 38.81 56.71 3 40.00 62.69 76.21 4 35.43 44.1376.43

[0063] TABLE 2 Reduction of Histamine-induced Guinea Pig IcumContractions (IC₅₀) Drug Expt IC₅₀ (M) Loratadine 1 1.90 × 10⁻⁸  2 2.21× 10⁻⁸  3 2.10 × 10⁻⁸  4 1.22 × 10⁻⁸  Mean 1.86 × 10⁻⁸  S.E. 0.22 DCL 16.36 × 10⁻¹⁰ 2 19.2 × 10⁻¹⁰ 3 5.26 × 10⁻¹⁰ 4 8.66 × 10⁻¹⁰ Mean 9.75 ×10⁻¹⁰ S.E. 3.20

[0064] Note: There is a statistically significant drug-relateddifference in IC₅₀ values (P=0.0209).

[0065] These results indicate that DCL is approximately 20 fold morepotent at the histamine receptor than loratadine.

5.3 Example 3 Receptor Binding Studies

[0066] Receptor binding studies on the binding affinities of loratadineand DCL at histamine H-1 receptors were performed.

[0067] The methods described by Dini et al., which is herebyincorporated by reference herein (Agents and Actions, 33: 181-184,1991), were used for these binding studies. Guinea pig cerebellamembranes were incubated with 0.5 nM 3H-pyrilamine for 10 min at 25° C.Following incubation, the assays were rapidly filtered under vacuumthrough GF/B glass fiber filters (Whatman) and washed several times withice-cold buffer using a Brandel Cell Harvester. Bound radioactivity wasdetermined with a liquid scintillation counter (LS 6000, Beckman) usinga liquid scintillation cocktail (Formula 989, DuPont NEN).

[0068] IC₅₀ values were determined for compounds tested and pyrilamineat the H-1 histamine receptor: TABLE 3 Inhibition of Pyrilamine Bindingat H-1 Receptor H-1 receptor Compound IC₅₀ (nM) (nH) Loratadine 721(1.55) DCL 51.1 (1.12) Pyrilamine 1.4 (0.98)

[0069] As shown above, DCL was found to have a 14 fold greater affinitythan loratadine for histamine H-1 receptors. These results areconsistent with the findings demonstrating a higher potency of DCL overloratadine for inhibition of histamine-induced contractions of guineapig ileum.

[0070] These studies confirm that-DCL has a higher potency for histaminereceptors than loratadine.

5.4 Example 4 Tumor Promoting Activity

[0071] Inhibition of lymphocyte mitogenesis was used to screen thepotencies of loratadine and DCL as tumor promoting agents.

Mitogenesis Studies

[0072] Fresh spleen cells (5×10⁵, obtained from 5-week old BALB/c mice(Charles River, ST. Constant, PQ) were suspended in RPMI 1640 mediumcontaining 2% fetal calf serum (Grand Island Biological Co., GrandIsland, N.Y.) seeded into replicate microwell plates (Nunc) to whichconcanavalin (Con) A (2 μg/ml; Sigma Chemical Co., St. Louis, Mo.) wasadded and incubated (37° C., 95% air, 5% CO₂) in the absence or presenceof increasing concentrations of the test agents dissolved in saline orother vehicles. Forty-three hours after the addition of Con A, 0.25 nmol³H-thymidine (6.7 Ci/nmol; ICN Radiopharmaceuticals, Montreal, PQ) wasadded to each well. After an additional 5-hour incubation, the cellswere washed from the wells onto filter papers employing an automatedcell sorter. The filters were placed into vials containing 5 mlscintillation fluid (Readysafe; Beckman), and radioactivity incorporatedinto DNA at 48 hours was determined (n=3). IC₅₀ values for inhibition ofmitogenesis were determined over wide range of concentrations (0.1 to 10μM). TABLE 4 Inhibition of Concanavalin A Induced Stimulation ofLymphocytes (IC₅₀) Loratadine 1.0 μM DCL 5.6 μM

[0073] These results indicate that DCL is 5-7 fold less active thanloratadine at promoting tumor growth.

5.5 Example 5 Cardiovascular Effects

[0074] The effects of DCL on cardiac potassium currents were studied.

Methods

[0075] Single ventricular myocytes of the guinea-pig and the rabbit weredissociated by enzymatic dispersion (see Carmeliet, J. Pharmacol. Exper.Ther., 1992, 262, 809-817 which is incorporated herein by reference inits entirety). The single suction patch electrode, with a resistance of2 to 5 MΩ was used for voltage clamp (Axoclamp 200A). P-clamp software(Axon Instruments) was used to generate voltage-clamp protocols and torecord and analyze data. The standard solution contained in mM: NaCl137.6, KCl 5.4, CaCl₂ 1.8, MgCl₂ 0.5, HEPES 11.6 and glucose 5, and NaOHwas added to pH 7.4. The intracellular solution contained KCl 120, MgCl₂6, CaCl₂ 0.154, Na₂ATP 5, EGTA 5, and HEPES 10, with KOH added until pH7.2.

Effect on the Delayed Rectifying K⁺ Current, (I_(kr)) in RabbitVentricular Myocytes

[0076] The voltage clamp protocol consisted of clamps from a holdingpotential of −50 mV to +10 mV for a duration of 4 sec. The change intail current was measured as a function of the drug concentration. Thisconcentration was changed between 10⁻⁷ and 10⁻⁵ M in five steps.Exposure to each concentration lasted 15 min. At the end, washout wasattempted during 30 min.

Effect on the Inward Rectifier Current in Guinea-pig Myocytes

[0077] The inward rectifier was measured by applying ramp voltage clampsstarting from −50 mV and hyperpolarizing the membrane to −120 mV at aspeed of 10 mV/sec. The starting concentration was the 50 efficiencyconcentration, determined in the preceding experiments. Higherconcentrations were applied if this initial concentration was withouteffect.

Effect on IK, in Guinea-pig Ventricular Myocytes

[0078] Tail currents were measured following depolarizing clamps of 2sec duration to potentials between −30 mV and +60 mV; holding potential−50 mV.

[0079] The results from these studies indicate that DCL is less activethan terfenadine in inhibiting the cardiac delayed rectifier and thushas no potential for cardiac side-effects. Thus, the methods of thepresent invention are less toxic than methods which use othernon-sedating antihistamines.

5.6 Example 6 Inhibition of Cytochrome P450

[0080] This study is conducted to determine the extent that loratadineand DCL inhibit human cytochrome P4503A4 (CYP3A4). CYP3A4 is involved inmany drug-drug interactions and quantitation of inhibition of CYP3A4 byloratadine or DCL indicates the potential of such drug-druginteractions. Inhibition is measured using the model substratetestosterone and cDNA-derived CYP3A4 in microsomes prepared from a humanlymphoblastoid cell line designated h3A4v3.

Study Design

[0081] The inhibition study consists of the determination of the 50%inhibitory concentration (IC₅₀) for the test substance. A singletestosterone concentration (120 μM, approximately twice the apparent Km)and ten test substance concentrations, separated by approximately ½ log,are tested in duplicate. Testosterone metabolism is assayed by theproduction of the 6(β)-hydroxytestosterone metabolite. This metaboliteis readily quantitated via HPLC separation with absorbance detection.

Storage/Preparation of the Test Substances and Addition to theIncubations

[0082] The test substances will be stored at room temperature. The testsubstances will be dissolved in ethanol for addition to the incubations.The solvent concentration will be constant for all concentrations of thetest substance.

IC₅₀ Determination

[0083] Final test substance concentrations will be 100, 30, 10, 3, 1,0.3, 0.1, 0.03, 0.01, 0.003 and 0 μM. Each test concentration will betested in duplicate incubations in accordance with the method below:

Method

[0084] A 0.5 ml reaction mixture containing 0.7 mg/ml protein, 1.3 mMNADP+, 3.3 mM glucose-6-phosphate, 0.4 U/ml glucose-6-phosphatedehydrogenase, 3.3 mM magnesium chloride and 120 μM testosterone in 100mM potassium phosphate (pH 7.4) will be incubated at 37° C. for 30 min.A known quantity of 11(β)-hydroxytestosterone will be added as aninternal standard to correct for recovery during extraction. Thereaction mixture will be extracted with 1 ml methylene chloride. Theextract will be dried over anhydrous magnesium sulfate and evaporatedunder vacuum. The sample will be dissolved in methanol and injected intoa 4.6×250 mm 5u C18 HPLC column and separated at 50° C. with a mobilephase methanol/water at a flow rate of 1 ml per min. The retention timesare approximately 6 min for the 6(β)-hydrdxy, 8 min for 11(˜)-hydroxyand 12 min for testosterone. The product and internal standard aredetected by their absorbance at 254 nm and quantitated by correcting forthe extraction efficiency using the absorbance of the 11(β)-hydroxy peakand comparing to the absorbance of a standard curve for6(β)-hydroxytestosterone.

Data Reporting

[0085] For each test substance, the concentration of6(β)-hydroxytestosterone metabolite in each replicate incubation isdetermined and the percentage inhibition relative to solvent control iscalculated. The IC₅₀ is calculated by linear interpolation.

[0086] Useful pharmaceutical dosage forms for administration of thecompounds used in the methods of the present invention can beillustrated as follows:

5.7. Example 7 Capsules

[0087] A large number of unit capsules are prepared by filling standardtwo-piece hard gelatin capsules each with 0.1 to 10 milligrams ofpowdered active ingredient, 150 milligrams of lactose, 50 milligrams ofcellulose, and 6 milligrams magnesium stearate.

5.8. Example 8 Soft Gelatin Capsules

[0088] A mixture of active ingredient in a digestible oil such assoybean oil, lecithin, cottonseed oil or olive oil is prepared andinjected by means of a positive displacement pump into gelatin to formsoft gelatin capsules containing 0.1 to 10 milligrams of the activeingredient. The capsules are washed and dried.

5.9 Example 9 Tablets

[0089] A large number of tablets are prepared by conventional proceduresso that the dosage unit was 0.1 to 10 milligrams of active ingredient,0.2 milligrams of colloidal silicon dioxide, 5 milligrams of magnesiumstearate, 275 milligrams of microcrystalline cellulose, 11 milligrams ofstarch and 98.8 milligrams of lactose. Appropriate coatings may beapplied to increase palatability or delay absorption.

[0090] Various modifications of the invention in addition to those shownand described herein will be apparent to those skilled in the art fromthe foregoing description. Such modifications are also intended to fallwithin the scope of the appended claims.

[0091] The foregoing disclosure includes all the information deemedessential to enable those skilled in the art to practice the claimedinvention. Because the cited patents or publications may provide furtheruseful information these cited materials are hereby incorporated byreference in their entireties.

What is claimed is:
 1. A method of treating allergic asthma in a humanwhile avoiding the concomitant liability of adverse side-effectsassociated with the administration of non-sedating antihistamines,comprising administering to a human a composition, said compositioncomprising (i) a therapeutically effective amount of DCL or apharmaceutically acceptable salt thereof; (ii) a therapeuticallyeffective amount of a decongestant; and a pharmaceutically acceptablecarrier.
 2. A method of treating allergic asthma in a human whileavoiding the concomitant liability of adverse side-effects associatedwith the administration of non-sedating antihistamines, comprisingadministering to a human a composition, said composition comprising (i)a therapeutically effective amount of DCL or a pharmaceuticallyacceptable salt thereof; (ii) a therapeutically effective amount ofleukotriene inhibitor selected from the group consisting of5-lipoxygenase inhibitors, 5-lipoxygenase activating proteinantagonists, and leukotriene D₄ antagonists; and a pharmaceuticallyacceptable carrier.
 3. A method of treating dermatitis in a human whileavoiding the concomitant liability of adverse side-effects associatedwith the administration of non-sedating antihistamines, comprisingadministering to a human a therapeutically effective amount of DCL or apharmaceutically acceptable salt thereof.
 4. The method of claims 1, 2,or 3 wherein said adverse side-effect is cardiac arrhythmia or tumorpromotion.
 5. The method of claims 1, 2, or 3 wherein the human has ahigher than normal propensity for or incidence of cancer.
 6. The methodof claims 1, 2, or 3 wherein interaction with a drug that inhibitscytochrome P450 is avoided.
 7. The method of claims 1, 2, or 3 whereinthe amount of DCL administered is from about 0.1 mg to less than about10 mg per day.
 8. The method of claim 7 wherein the amount of DCLadministered is from about 0.1 mg to about 5 mg per day.
 9. The methodof claim 1 wherein the amount of DCL is from about 0.1 mg to about lessthan about 10 mg and the amount of decongestant is from about 50 mg toabout 300 mg per day.
 10. A method of treating allergic asthma in ahuman while avoiding the concomitant liability of adverse side-effectsassociated with the administration of non-sedating antihistamines,comprising administering to a human a therapeutically effective amountof DCL and a therapeutically effective amount of a decongestant.
 11. Amethod of treating allergic asthma in a human while avoiding theconcomitant liability of adverse side-effects associated with theadministration of non-sedating antihistamines, comprising administeringto a human a therapeutically effective amount of DCL and atherapeutically effective amount of a leukotriene inhibitor.
 12. Apharmaceutical composition consisting essentially of an amount of DCLfrom about 0.1 to about less than 10 mg and about 50 mg to about 300 mgof decongestant.
 13. A pharmaceutical composition which comprises atherapeutically effective amount of DCL and a therapeutically effectiveamount of a leukotriene inhibitor selected from the group consisting of5-lipoxygenase inhibitors, 5-lipoxygenase activating proteinantagonists, and leukotrilene D₄ antagonists.
 14. The method of claims1, 2 or 3 wherein the compositions are administered as a nasal or oralspray.
 15. The method of claim 10 wherein the DCL is administered as anasal or oral spray.
 16. The method of claim 11 wherein the DCL isadministered as a nasal or oral spray.